The present invention relates to the field of hinges and, specifically, to seat hinges of the type used for foldable boat seats. Such seats commonly have a back that can fold down over the seat and are usually provided with a strap having a snap at the end to hold the seat in a folded position.
The hinge that is most commonly used is a pair of metal angles fastened together with a large rivet. One angle is bolted to the seat bottom and the other to the seat back so that the rivet serves as a pivot for the hinge. These metal hinges can pinch the fingers of the user if the user puts a hand between the parts of the hinge while the seat is being pushed upright.
Another hinge commonly used is made out of two pieces, molded from a resistant material, each having a hinge guide portion which surrounds the pivot point of each of the two pieces. The hinge guide portion has a form which is an arc drawn about the pivot point, the two arcs fitting closely with one another and never separating regardless of the orientation of the seat back. The various hinge positions always result in the two hinge guide portions overlapping one another without any gap; therefore not allowing a person to pinch her fingers in the process.
For example, U.S. Pat. No. 5,052,076 to Spaeth, discloses a seat back hinge in which the hinge pivot has a generally circular outer pivot wall on one section of the hinge, and a generally circular inner pivot wall on the other section of the hinge. The inner wall is of a size that allows it to fit closely inside the outer wall. The inner wall is provided with ears that project at right angles to the top of the inner wall and the outer wall is provided with relieved sections or bays that allow the ears to pass through the outer wall in only one orientation. Concentric shield portions keep fingers of an user out of the hinge. Integral stops limit movement and an integral leaf spring catches a detent to lock the hinge in one position.
Yet another prior art seat back hinge is made out of two sections coupled by means of a fastener and two plastic pins. The first section has one planar and circular end having a first aperture and two arcuate channels formed therein surrounding the first aperture. The second section has a corresponding planar and circular end parallel to the end of the first section. The second section end further includes three apertures disposed to be aligned with the first aperture and the two arcuate channels. The hinge further comprises a planar and circular intermediate plate, parallel and adjacently coupled to the first section end and the second section end. The intermediate plate has three intermediate apertures disposed to be aligned with the other apertures and the two arcuate channels. The hinge further comprises a planar and circular back plate, parallel and adjacently coupled to the first section end, opposite to the intermediate plate. The back plate has three back apertures disposed to be aligned with the other apertures and with the two arcuate channels. The intermediate plate and the back plate are made out of plastic. The single fastener is made out of steel and the pins are made out of plastic. The plastic pins are perpendicular to the ends of the two sections, the intermediate plate and the back plate and housed within the apertures and the arcuate channels. When pressure is applied to the seat back in its upright position, this type of hinge has the tendency to fail, therefore destroying the entire seat.
It is an object of the present invention to provide a seat hinge comprising three pieces and three fasteners, which require a simple assembly operation. It is a further object of this invention to provide a seat hinge which is formed from inexpensive materials. It is also an object of this invention to provide a seat hinge offering additional strength and improved reliability to the foldable boat seat.